As semiconductor technology advances, certain device wear-out mechanisms have become more and more prominent, which the inventors believe may start to severely impact the stability and functionality of product circuits within their specified lifetime. Semiconductors are increasingly built utilizing high-κ dielectrics to allow for faster speeds and smaller sizes. The term high-κ dielectric refers to a material with a high dielectric constant κ (as compared to silicon dioxide) used in semiconductor manufacturing processes which replaces the silicon dioxide gate dielectric. The implementation of high-κ gate dielectrics is one of several strategies developed to allow further increase in device speed and miniaturization of microelectronic components, colloquially referred to as extending Moore's Law. Silicon dioxide has been used as a gate oxide material for decades. As transistors have decreased in size, the thickness of the silicon dioxide gate dielectric has steadily decreased to increase the gate capacitance and thereby drive current and device performance. As the thickness scales below 2 nm, leakage currents due to tunneling increase drastically, leading to unwieldy power consumption and reduced device reliability. Replacing the silicon dioxide gate dielectric with a high-κ material allows increased gate capacitance without the concomitant leakage effects.
The inventors have noted that during the operation of a NFET (Negative Channel Field Effect Transistor) with a high-κ material, electrons migrate towards the gate oxide and tend to reduce the operation of the transistor. As stated above due to the decrease in the thickness and overall size of the components on a silicon dioxide chip, the effect of electrons trapped in the transistor gate dielectric is significantly increased.
In a similar manner the inventors have identified that during the operation of a PFET (Positive Channel Field Effect Transistor) with a high-κ material, holes tend to build up in the gate oxide. Again due to the decrease in the thickness and overall size of the components on a silicon dioxide chip, the effect of the holes trapped in transistor gate dielectric is significantly increased.
Due to detrimental affects of the build up of electrons in NFETs and holes in PFETs in their gate dielectrics, the inventors have determined that a method and apparatus for repairing or tuning transistors would be desirable.